The second screening consists of an ultrasound examination and a triple test for the level of hCG hormone, AFP protein and free estriol. These tests should confirm or refute the data obtained during the first screening examination.

If, during the second screening, the level of substances such as human chorionic gonadotropin (hCG), alpha-fetoprotein (AFP), and free estriol is determined in a woman’s blood, then the test is called. If the second screening during pregnancy also includes a blood test for inhibin A, in this case the test is already called. A study of the concentration of these specific hormones and proteins in the blood of a pregnant woman makes it possible, with a certain degree of probability, to speak about the risk of developing such developmental defects in the fetus as Down syndrome (trisomy 21), Edwards syndrome (trisomy 18), neural tube defects (spinal cleft and anencephaly) . Changes in the results are carefully studied, compared with standard indicators, and appropriate conclusions are drawn. Based on these data, information is obtained about the intrauterine state of the child. If it is positive, all that remains is to wait for his safe birth. If negative, it is necessary to take appropriate measures - either prescribe treatment or artificially induce premature birth.

Who is prescribed the second screening?

The indications for the second screening remain the same as for the first screening, namely:

• women whose age at the time of pregnancy is 35 years or older
• women who have hereditary diseases
• women who have had viral diseases during early pregnancy;
• if previous pregnancies ended in fetal death, stillbirth
• if the baby is from a consanguineous marriage
• if the expectant mother uses drugs or medications prohibited during pregnancy;
• if the mother suffers from alcoholism
• if the first children have genetic disorders;
• if the expectant mother has harmful working conditions;
• if there have been miscarriages or terminations of pregnancy in the past.

Additional indications for a second screening are:

• the first screening during pregnancy showed a threshold or high level of probability of the fetus having malformations;
• if an acute infectious or bacterial disease occurs in the mother after the 14th week;
• if the mother was diagnosed with a neoplasm in the second trimester.

If the pregnancy proceeds without complications, and the expectant mother is confident that the baby is healthy, then a second screening is not carried out. However, if a woman herself expresses a desire to undergo it in order to get rid of unnecessary worries, doctors will not refuse her.

When is the second screening done during pregnancy?

Ultrasound examination

• no earlier than the 16th week;
• no later than the 20th;
• the most successful period is the entire 17th week: this will allow you to pass additional examinations from a geneticist when identifying abnormalities.

Biochemical test

Blood for biochemical analysis should be taken strictly from the 16th week to the 6th day of the 18th week of pregnancy.

What research is being done

Second trimester screening includes:

• ultrasound examination
• biochemical study (blood test). Three hormones are being studied: free b-subunit of human chorionic gonadotropin (free b-hCG), PAPP-A (plasma protein A associated with pregnancy), and free estriol, a female sex hormone, the activity of which, under the influence of hCG, sharply increases in a woman’s blood after fertilization .The level of estriol affects the state of the uteroplacental blood flow, the development of the uterus, as well as the formation of ducts in the mammary glands of the expectant mother.

Sometimes to the expectant mother They may additionally prescribe another analysis. Inhibin A is a specific female hormone, an increase in the level of which in a woman’s blood is characteristic of pregnancy. Its content in the blood of the expectant mother depends on the timing and condition of pregnancy and the fetus. It is produced by a woman’s ovaries, and in a state of expecting a baby – by the placenta and the body of the embryo.

Inhibin A is rarely taken into account in the second screening study for calculating the risk of fetal malformations - mainly when the previous 3 parameters do not give an unambiguous picture.

What is determined by research results

Ultrasound examination

• thickness, location, degree of maturity and structure of the placenta;
• condition of the uterus, its cervix and appendages;
• volume of amniotic fluid;
• baby parameters (volume of the chest, abdomen and head, length of paired bones on each side);
• development of the brain and spine;
• facial development (eyes, mouth, nose);
• development of the heart and large blood vessels;
• condition of vital organs: kidneys, bladder, intestines, stomach.

Blood chemistry:

• plasma protein level (designated PAPP-A);
• the content of human chorionic gonadotropin (the conclusion should contain the column “free β-hCG”).
• free estriol E3

How to prepare for analysis

• The bladder does not have to be full as at the first screening. Large volume amniotic fluid allows you to perform a high-quality ultrasound procedure.
• And even the fullness of the intestines does not play a special role either. In the second trimester, this organ is crowded by the enlarged uterus and does not interfere with ultrasound examination.
• And yet, a day before the second screening ultrasound, you need to give up allergenic foods: chocolate, citrus fruits, cocoa, seafood, fried and fatty foods.
• On the day of the blood test, you should not eat anything - this may distort the test results.
• You cannot allow bad thoughts: you need to pull yourself together and set yourself up positively.

It is not difficult to prepare for the second screening, because you already have experience from the first. This means that it will be easier to organize yourself informationally. And although the studies are somewhat different from the previous ones, the scheme for conducting them will be approximately the same.

Second screening during pregnancy norms:

Ultrasound examination:

The norms of several examples of the fetus, which the doctor evaluates using ultrasound screening in the 2nd trimester (16-20 weeks):

Biparietal size (BPD) (mm)

• 16 weeks – 31 – 37 mm
• 17 weeks - 34 - 42 mm
• 18 weeks - 37 - 47 mm
• 19 weeks - 41-43 mm
• 20 weeks - 43-53 mm

Head circumference (mm)

• 16 weeks – 112 – 136 mm
• 17 weeks - 121 -149 mm
• 18 weeks - 131 - 161 mm
• 19 weeks - 142 - 174 mm
• 20 weeks - 154 - 186 mm

Abdominal circumference (mm)

• 16 weeks – 88 – 116 mm
• 17 weeks - 93 - 131 mm
• 18 weeks - 104 - 144 mm
• 19 weeks - 114 - 154 mm
• 20 weeks - 124-164 mm

Fronto-occipital size (mm)

• 16 weeks – 41 – 49 mm
• 17 weeks - 46 - 54 mm
• 18 weeks – 49 – 59 mm
• 19 weeks - 53 - 63 mm
• 20 weeks – 56 – 68 mm

Femur bone length (mm)

• 16 weeks - 17 - 23 mm
• 17 weeks - 20 - 28 mm
• 18 weeks - 23 - 31 mm
• 19 weeks -26 – 34 mm
• 20 weeks - 29 - 37 mm

Shoulder bone length(mm)

• 16 weeks – 15 – 21 mm
• 17 weeks – 17 – 25 mm
• 18 weeks - 20 - 28 mm
• 19 weeks -23 – 31 mm
• 20 weeks – 26 – 34 mm

Amniotic fluid index (mm)

• 16 weeks – 73 – 201 mm
• 17 weeks - 77 - 211 mm
• 18 weeks – 80 – 220 mm
• 19 weeks - 83 - 225 mm
• 20 weeks – 86 – 230 mm

Blood chemistry:

The values ​​accepted as norms for the indicators studied during the laboratory analysis of the patient’s blood, as part of the second screening, may vary, depending on the ethnic composition of the region in which the laboratory is located and for which the diagnostic computer program settings are made.

Blood biochemistry for the second screening shows not only hCG level, but also reveals other indicators important for the second trimester of pregnancy.

Estriol (E3)

Alpha fetoprotein (AFP)

Without these blood parameters, interpretation of the second screening is impossible. Their risk level is calculated based on the MoM coefficient as during the first screening

MoM

The level of deviations, taking into account factors such as age, weight and illnesses suffered by the woman, is included in a certain coefficient. For the second trimester of pregnancy, MoM norms are presented in the following figures:

• lower limit 0.5;
• top - 2.5;
• the optimal indicator is 1.

Based on the MoM, the risk of developing abnormalities in an unborn child is calculated. If it is 1 in 380, this is considered normal. But as soon as the second figure begins to decline, this indicates that the chance of giving birth to a healthy and full-fledged child is just as low.

How can you find out from the certificates received after the second screening how normally the pregnancy is developing? It all depends on the degree of deviation.

Deviations from the norm

To assess the values ​​of screening markers honey. institutions use computer programs specially developed for diagnostic purposes, which calculate the risks of certain abnormalities taking into account the values ​​of all test indicators in the aggregate, including data from the ultrasound protocol. This is called combined screening. Moreover, the result is determined with an adjustment for each specific case. The individual history of the expectant mother is taken into account: multiple pregnancy, pregnancy due to IVF, bad habits, weight, age, chronic diseases etc. In addition, when screening the second trimester, the primary results of the examination conducted during the period 10–14 weeks of pregnancy are also entered into the database for calculating screening risks. Only such an integrated approach for the purposes of non-invasive prenatal diagnosis of possible pathologies of fetal development is as reliable as possible. It makes no sense to consider each indicator separately for the purpose of a screening examination. Firstly, the list of possible reasons influencing the difference of each individual component from the average statistical norm is quite large. Secondly, even a significant deviation from the normal values ​​of any one hormone being determined is not always indicative of screening risks. For example, even with multiple deviations of the AFP level from the norm, if you ignore the values ​​of other indicators, the risk of fetal deformities is possible only in 5% of cases. And with the prenatal diagnosis of a disease such as Patau syndrome, AFP level will not cause concern at all. Therefore, only with a cumulative analysis of the values ​​of all biochemical markers can assumptions be made about the likelihood of developing congenital malformations of the fetus.

False results

Although rare, this does happen: second trimester screening produces false results. This is possible if the course of pregnancy is characterized by the following features:

• multiple pregnancy;
• incorrect deadline;
• excess weight overestimates the indicators, underweight underestimates them;
• diabetes.

Before conducting the second screening, the gynecologist must identify these factors using a questionnaire and a preliminary examination and take them into account when drawing the results. It is on this that further actions to maintain or terminate the pregnancy will depend.

When a second ultrasound is performed during pregnancy, the doctor differentiates the sex of the unborn baby. This perinatal screening, otherwise comprehensive examination, is planned, and is carried out to identify possible pathologies in the child. In obstetrics, official dates are defined, but they can be changed by the decision of the obstetrician-gynecologist leading the pregnancy if the doctor has doubts about the positive dynamics of embryo development.

Time range for second screening

During pregnancy, the condition of the woman and fetus should be monitored using screening three times. In the first, 2nd trimester, and third, respectively. All examinations are important for a woman and child. The need for a second screening during pregnancy is due to the possibility of preventing various pathologies in the future, or identifying existing ones. During this period, the doctor can already examine the future baby in detail and assess the degree of its development. internal organs.

As for the timing of the 2nd planned ultrasound, usually the time range from the 20th to the 23rd week is selected. These are general indicators. The doctor should decide exactly at what time to do the second ultrasound during pregnancy, based on the patient’s individual indicators. If the doctor has any doubts, the examination may be carried out earlier.

In addition to the ultrasound procedure, a woman must undergo hormonal blood biochemistry. Medical experts advise doing this before ultrasound examination. The results of biochemical analysis are extremely important for a deeper assessment of the condition of the mother and fetus. The list of essential hormones, the level of which will tell the doctor about possible problems, includes:

• Alphatoprotein (AFP protein). Provides the child with nutrients.
• Human chorionic gonadotropin (hCG). The so-called pregnancy hormone is responsible for preserving the fetus. It is produced from the second trimester, and its quantity gradually increases.
• Free estriol (E3). Female sex hormone. Affects the condition and development of the uterus and uteroplacental blood circulation. An increase in this hormone indicates an unhealthy condition of the mother (inflammation and infection of the liver and kidneys).

Special indications

There is a so-called risk group - pregnant women with any abnormalities. For such women, screening is mandatory if indicated. These include:

• late pregnancy(women aged 35+);
• genetic abnormalities in expectant mothers and fathers, or their older children;
• repeated spontaneous termination of previous pregnancies (miscarriages);
• a woman’s stay in the radiation zone;
• abnormal fetal development identified during previous ultrasound examinations.

Preliminary preparation for screening, regardless of how many weeks it is carried out, is not necessary.

Second trimester ultrasound screening is a desirable stage of pregnancy

Assessment of organs and systems during repeated ultrasound

During the second screening during pregnancy, the gynecologist assesses the health status of the woman and baby. The expectant mother is studying:

• the main organ connecting the embryo and mother (placenta). The location, thickness and structure of the “children's place” are subject to analysis;
• the living environment where fetal development occurs (amniotic fluid). Their number is estimated;
• umbilical cord vessels. The emphasis is also on quantity;
• female reproductive organs (uterus with appendages and cervix).

From health status maternal body, at any stage of pregnancy, the vital activity of the embryo depends. A second planned ultrasound during pregnancy helps to collect maximum data on the child’s health status, identify and assess the degree of deviation from the norm for a given period of development.

The following parameters are analyzed:

• the location of the fetus itself in the womb;
• bony frame of the head and facial bones;
• the main rod of the entire skeleton (vertebral column);
• maturity of the bronchopulmonary system;
• degree of heart development;
• state of brain structures;
• genitourinary and digestive systems;
• general compliance with developmental norms (fetometry).

In addition, ultrasound in the second trimester can show possible external genetic abnormalities (improper development of legs, arms, fingers). During the second ultrasound during pregnancy, the doctor determines the following dimensional indicators in the child: head and abdominal circumference, length of the thigh and lower leg bones, length of the humerus and forearm bones, fronto-occipital size of the fetus.

The woman receives the diagnostic results in her hands on the same day

The correct dimensions of good intrauterine development, which are shown by the second screening ultrasound performed at the twentieth week of pregnancy, are:

• head and abdominal circumference: 154–186 mm and 124–164 mm, respectively;
• fronto-occipital size: 56–68 mm;
• length of the femur and tibia bones: 29–37 mm and 26–34 mm;
• length of humerus and forearm: 26–34 mm and 22–29 mm.

Hormonal tests determine the abnormal development of the nervous system, heart, esophagus, umbilical hernia, and the risk of miscarriage in the mother. In addition, tests of the expectant mother and ultrasound examination the second trimester will show more serious abnormalities. During the second screening, a medical specialist can identify the presence of the most severe defect of the nervous system, anencephaly, in the child, a serious form of genomic pathology - Down syndrome and chromosomal pathology trisomy 18 syndrome, known as Edwards syndrome. As well as rare genetic diseases Turner syndrome and Patau syndrome.

Screening results are assessed only as a whole. If abnormal development of the child is detected during an ultrasound, it is better for the woman to go to the hospital, where many additional tests are performed. In particular, amniocentesis. This is a complex procedure for collecting amniotic fluid for analysis. The operation is risky, but the accuracy of the results is more than 95%.

The doctor should give the necessary recommendations. Perhaps the question of terminating the pregnancy will arise. Beyond 22 weeks, medical abortion is no longer possible, and the method of artificial childbirth causes the woman both physical pain and psychological suffering. The decision, in any case, depends on the woman.

Factors influencing results

When screening is done, there may be some errors in the results. This may depend on the condition of the equipment and the qualifications of the medical specialist. There are also other influences:

• age-related changes woman’s body (age 35+);
• unhealthy antisocial lifestyle (drugs, alcohol, nicotine). These reasons make pregnancy initially complicated;
• hormonal dependence. The expectant mother has diseases, the treatment of which requires constant use of hormone-containing drugs;
• chronic pathologies during exacerbation;
• body mass. In obesity, blood counts are always elevated. Lack of weight, on the contrary, reduces performance;
• non-natural fertilization (IVF);
• the child is too big;
• multi-embryonic pregnancy (twins, triplets, etc.).

Second trimester screening can determine the presence of pathologies in the fetus

If fetal pathologies are detected, you should not panic; you need to do an ultrasound again. Change the clinic or specialist, wait for remission of the disease, and perform an amniocentesis procedure.

Ultrasound of the 2nd trimester is an extremely important procedure during the period of bearing a baby. The results provide a prognosis for the further course of pregnancy and the stage of health of the future newborn. Constant monitoring by a doctor in time will prevent possible complications, and with the correct course of pregnancy it will provide peace of mind to the woman.

Modern methods of monitoring the health of the expectant mother during pregnancy involve three screenings -. Each comprehensive examination includes completion and evaluation of the results.

Dates

The optimal time for the second screening is from before pregnancy. At this time, the doctor has the opportunity to determine the presence of defects or disorders that could not be identified during the first examination.

Many experts recommend undergoing a second screening examination in order to be able to undergo additional examination or make an appointment with a geneticist if a high degree of likelihood of developing any diseases in the fetus is detected.

Types of research

The second prenatal screening consists of the following types of examinations:

• – performed using a transabdominal sensor (through the skin of the abdomen). During the procedure, the doctor evaluates not only the growth and development of the fetus, but also the condition.
• . In laboratory conditions, a specialist determines the content, and.

First, it is advisable for the expectant mother to undergo an ultrasound scan, and based on the results of this examination, the doctor decides on the need for a blood test from a vein.

Preparing for screening

In preparation for the second prenatal screening Much fewer requirements are placed on the woman than before the first examination. There is no need to specifically fill the bladder with liquid, because the fetus is already surrounded in sufficient quantities at this time.

The condition of a pregnant woman’s intestines is also not of great importance during an ultrasound scan, since this organ is moved back enlarged. However, the day before the examination, it is advisable to avoid foods such as:

• citrus;
• fried and fatty foods.

important The morning before donating blood from a vein, you must refrain from breakfast.

Standard values

During the second screening, the doctor pays great attention to determining a number of indicators and hormone levels in the blood of a pregnant woman, and then compares them with the recommended standard values. Depending on the stage of pregnancy, these data should be:

• – determined to assess the size of the fetal head. The standard values ​​for this indicator are as follows: – 35 mm; – 39 mm; – 42 mm; – 44 mm; – 47 mm.
• Thigh Length(DB) should approach the following norm: at week 16 – 22 mm, at week 17 – 24 mm, at week 18 – 28 mm, at week 19 – 31 mm, at week 20 – 34 mm.
• Abdominal girth (AB) should be: at week 16 – from 88 to 116 mm; at week 20 – from 124 to 164 mm.
• determined starting from week 20 - during this period it should be from 16.7 to 28.6 mm and have a “zero” degree of maturity.
• can range from 80-200 mm (at 16 weeks) to 93-130 mm (at 20 weeks).
• should be: at week 16 – from 10 thousand to 58 thousand honey/ml; at 17-18 weeks – from 8 thousand to 57 thousand honey/ml; at week 19 – from 7 thousand to 49 thousand honey/ml; at week 20 – from 4.7 thousand to 47 thousand honey/ml.
• must meet the following indicators: at week 16 – from 5.4 to 21 nmol/l; at 17-18 weeks – from 6.6 to 25 nmol/l; at 19-20 weeks – from 7.5 to 28 nmol/l.
• is: for a period of 16-19 weeks – from 15 to 95 U/ml; at week 20 – from 27 to 125 U/ml.

important Also, during an ultrasound, they measure, determine the degree of development of its organs and other indicators that are of great importance for identifying possible abnormalities.

Deviation from norms

After performing an ultrasound and receiving the results, the doctor not only compares the results obtained with standard values, but also calculates the degree of risk based on the likelihood of a particular pathology occurring.

Actual screening rates are divided by the average obtained by processing data from previous studies that included women of approximately the same age living in the area.

The result obtained is denoted by the abbreviation “MoM”.

If the MoM value is between 0.5 and 2.5, it is considered normal indicator. The closer the obtained result approaches one, the better the screening result.

The total result of the second screening is recorded as a fraction, for example, 1:500.

• If the denominator in this expression is greater than 380, this is a normal result (eg 1:400 or 1:1000).
• If the number in the denominator is less than 380(for example, the result is 1:290), then the likelihood of certain abnormalities in the fetus is quite high.
• If the obtained indicator is in the range from 1:250 to 1:360, it is advisable for the expectant mother to consult a geneticist.
• At risk level 1:100 It is recommended to carry out invasive diagnostics to determine the chromosome set of the fetus.

The expectant mother should remember that the probability of receiving a false positive screening result is about 10%, and a false negative one – up to 30%.

additionally You should not panic if the doctor reports the presence of some possible abnormalities in the fetus. In this case, it is necessary to undergo additional types of examinations in order to clarify the data obtained.

It is very important to remain calm and confident when undergoing screening, because psychological mood Women are significantly affected by the level of hormones in the blood.

After passing the second screening, you should also follow the doctor’s recommendations regarding lifestyle, physical activity, in order to increase the likelihood of having a healthy child.

All examinations that the doctor prescribes cause anxiety in some patients. This is especially true for pregnant women, when they have to bear responsibility not only for themselves, but also for the unborn baby. This article will talk in detail about one such study - screening in the second trimester. How is the second screening performed during pregnancy? What is the time frame for the examination? When should you come to the clinic? What does the research include? During the second screening during pregnancy, you should undergo some tests. Let's look at which ones in detail.

Thus, you should not ignore the timing of the second screening during pregnancy.

Second trimester screening indicators

There are few such indicators, the main ones are the following:

• Head circumference;
• length of humerus bones;
• length of forearm bones;
• length of femurs;
• abdominal circumference;
• shin length;
• fronto-occipital size;
• biporiental size;
• amount of amniotic fluid.

These indicators provide complete information about the development of the fetus, the absence or presence of any anomalies in the structure.

What influences the results of a screening study?

If the screening examination was successful and all the results obtained correspond to the norms, then, most likely, the child will be born healthy. However, in any survey there is an error, and even if not very good results there is a chance of having a healthy baby. Also, and vice versa, a fetus that is considered healthy throughout pregnancy may be diagnosed with pathologies after birth. The results of the screening examination can be influenced by various factors, especially the biochemical test. Results may be distorted due to:

• chronic maternal diseases (for example, diabetes);
• bad habits of a pregnant woman (alcohol, smoking, drugs);
• woman's weight ( overweight contributes to exceeding the indicators, and insufficient weight - to underestimating);
• multiple pregnancy;
• pregnancy using IVF.

In conclusion

In case of severe pathologies of the fetus, the woman must be prescribed additional examinations, called invasive methods, as well as additional ultrasound. Even if severe deformities and pathologies incompatible with life are identified, only the woman makes the decision to terminate or continue the pregnancy. Doctors can only recommend one way or another way out of the current situation. Even with repeated confirmation of the pathology and high reliability of the data, the woman has the right to insist on continuing the pregnancy.

This is how screening is carried out in the second trimester of pregnancy, the timing of which is of great importance.

A screening examination of a pregnant woman is a set of methods that are used to detect or refute the development of anomalies, pathologies, and indirect markers (signs) in the fetus.

Second trimester in the fetus from pathologies
Process Examination of the fetus on the monitor
pregnant woman being examined by a doctor

Perinatal screening is a medical, laboratory ultrasound procedure that identifies risk groups for the occurrence of defects in the fetus throughout pregnancy.

Types of perinatal screening:

• perinatal screening in the 1st trimester from 10 to 14 weeks of pregnancy, this study includes a double test;
• perinatal screening of the 2nd trimester from 16 to 23 weeks of pregnancy, during this period a triple or quadruple gestation test is done;
• perinatal screening of the 3rd trimester is done from 30 to 32 weeks, the first and second trimesters are examined, and an integral test is done.

Based on the above, it follows that during pregnancy you need to undergo at least three mandatory ultrasound tests. There is no need to carry them out often unless absolutely necessary.

The timing is determined by the gynecologist with whom you are being examined, and they are selected individually for each pregnancy. A .

The optimal timing for the second screening (second trimester) is from 16 to 18 weeks. What does such an examination include:

• carry out an extensive ultrasound examination;
• biochemical examinations are prescribed in order to determine the level of hCG or free b-subunit of hCG, free estriol, inhibin, AFP.

Screening after 12 weeks

When performing perinatal screening in the second trimester, all ultrasound data that were obtained during examination in the first trimester and biochemical analysis indicators that were obtained from 16 to 19 weeks of pregnancy are taken into account.

The second screening examination, which is done between 20 and 24 weeks, allows us to identify many possible anomalies anatomical analysis. For example, such as:

• defect of the brain, spinal cord;
• liver defects;
• gastric tract abnormalities;
• the presence of a facial cleft;
• heart disease;
• defect in the development of limbs.

In most cases, anomalies that are detected in the middle of gestation are not subject to surgical treatment, and doctors often recommend terminating the pregnancy at this stage.

Also, when an ultrasound examination is performed in the 2nd trimester, the presence of markers of fetal chromosomal pathologies is assessed, such as:

• delay in embryo development;
• high, low water;
• pyeelectasia;
• ventriculomegaly;
• insufficient length of the tubular bone;
• reduced size of the nasal bone of the fetus;
• choroid plexus cyst of the brain and many other anomalies.

The doctor may prescribe a second ultrasound examination from 16 to 19 weeks of pregnancy. This happens for special indications that were obtained in a complex of ongoing studies. The gynecologist sends the pregnant woman to the laboratory. There are necessary tests systems, high-quality equipment with which you can do screening.

If risks of a congenital defect or anomaly are identified, the pregnant woman is sent to a medical genetic center, which can also be called a screening center. There are similar laboratories in all regional city centers. You can also go there without a doctor’s referral.

Fetal check

Biochemical laboratory tests

Biochemical screening, which is carried out in the 2nd trimester, is a determination of the presence of specific substances in the blood that vary depending on pathologies.

When a woman is pregnant, she undergoes a similar screening for developmental defects of the neural tubes (brain and spinal cord), chromosomal abnormalities (Down syndrome, Edwards syndrome).

A biochemical examination cannot accurately make a diagnosis; it can be used to identify high or low growth of pathology. In order to establish an accurate diagnosis, additional studies (ultrasound, invasive diagnostics, etc.) will be required.

Some experts argue that such studies should be prescribed to all pregnant women, because no one is immune from pathologies. Therefore, WHO recommends that all pregnant women undergo biochemical screening in the 2nd trimester.

But there is also an opinion that such studies should only be done by those who are at risk. Now in our country only women from this group are sent free of charge; the rest have to pay for it.

The following women are at risk:

• whose age is more than 35 years;
• who already have a child with chromosomal abnormalities;
• the child's father is a close relative;
• at the beginning of pregnancy, various drugs were taken that are contraindicated for a pregnant woman (cytostatics, antiepileptic drugs);
• there were previously more than two miscarriages and missed pregnancies;
• long-term threat of miscarriage;
• abnormalities during ultrasound examination;
• exposure of one of the parents to radiation before conception.

Often, biochemical screening is prescribed for the 2nd trimester, from 15 to 20 weeks or from 16 to 18. At this stage, three indicators are determined: AFP, hCG and NE.

A blood test will help determine if there are any inaccuracies in development

Procedure process

Screening is carried out in the 1st, 2nd and 3rd trimesters. As a rule, there are several stages. To begin with, they do this, thanks to which the thickness of the collar zone and the condition of the chorion are checked. The presence of Down syndrome is determined by the indicators of the cervical collar.

Additional tests of the chorionic villus are prescribed for women who have suffered a miscarriage, who are over 35 years old, and those who have genetic abnormalities in their family.

The second stage of the examination, or second screening, determines detailed fetal abnormalities. The level of general development and the degree of deviation of amniotic fluid from the normal state are checked. This is done at 16–20 weeks of pregnancy. An ultrasound shows the sex of the unborn child. Determine the size of the arms and legs. Blood is taken from a vein.

How to prepare for screening.

1. You should not drink a lot of fluids before going for the examination.
2. You should also not eat before the examination; it is better to refrain from eating for at least four hours.
3. If the ultrasound is performed abdominally, then you need to drink at least one liter of water.
4. Before taking blood, you must follow a diet for three to four days. It consists of eliminating foods such as chocolate, meat, fish, seafood, fatty, salty and fried foods.

First, an ultrasound examination is performed, and with the results you go to donate blood from a vein. During this, the specialist will talk with you and ask the necessary questions in such cases. This is done in order to accurately determine your result.

In about a few weeks you will receive the result. You should not independently decipher the results of the screening that you had in the 2nd trimester. The doctor will do this accurately and tell you everything in detail.

A good screening result is if the ACE level in the blood serum at approximately 15 to 19 weeks is from 15 to 95 U/ml. A bad result is if the protein level increases - this may indicate the presence of a malformation of the neural tubes, esophageal atresia, liver necrosis, umbilical hernia and so on.

If the protein is low, this may indicate a risk of developing Down syndrome, Edwards syndrome, or fetal death.

In any case, each indicator is individual; for one pregnant woman, exceeding any indicator is considered normal, for another, the same indicators are a deviation from the ultrasound norm.

Therefore, it is necessary to look at the results only with specialists, so as not to worry in vain. Based on each of your individual tests, the doctor will accurately determine your risks and be able to predict pregnancy.

If necessary, you will be prescribed a consultation with geneticists and qualified treatment.

Procedure process

Location of analysis

The test can be taken at clinics in different cities. Some of them are presented in the table.

: Borovikova Olga

gynecologist, ultrasound doctor, geneticist